Change "mediatek,rsel_resistance_in_si_unit" to "mediatek,rsel-resistance-in-si-unit"

Fixes: fb34a9ae ("pinctrl: mediatek: support rsel feature")
Signed-off-by: Guodong Liu <guodong.liu@mediatek.com>
Link: https://lore.kernel.org/r/20220216032124.28067-4-guodong.liu@mediatek.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>